<!doctype html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
</head>
<body>
<script>
var str = 'aaa';
alert(str.strike());		//	<strike>aaa</strike>

var str = 'aaaa';
alert(str.strike());		//	<strike>aaaa</strike>

</script>
</body>
</html>